I40 



PLANT LIFE. 



cells, consists of resinous or other protective substance 

 intended to keep off insects. (4) Chains of variously 

 shaped cells, which unite the upper epidermis to the 

 lower, and which leave many spaces between them — 



Fig. 16. — Transverse Section of a Leaf. From above downwards, first 

 the narrow thick-walled "epidermis" cells. Next two rows of long, upright 

 " palisade" cells with many round chlorophyll bodies in each. To the right a 

 large resin-gland, which is protective. From the palisades to the lower epidermis, 

 which is pierced by a pore or stoma where the arrows enter, are the loose spongy 

 cells, and in them, not quite half way down, is a nerve or vascular bundle consisting 

 of spirally marked xylem vessels above a few phloem tubes. Both are enclosed 

 in a circle of cells or bundle sneath. 



some of these have chlorophyll bodies and others none. 

 (5) A small nerve is shown in section near the centre. 

 It consists of two or three waterpipes or xylem trackeids, 

 with spirally wound thickenings, and below these of a 

 few food conducting cells or phloem ; both are sur- 

 rounded by a circle of cells, the inner-skin or endo- 



